Systemic lupus erythematosus (SLE), or lupus, is a chronic autoimmune disease where the immune system attacks its own healthy tissues and organs. This leads to inflammation and damage in various body parts, including the skin, joints, kidneys, and brain. Lupus symptoms are diverse and can mimic other conditions, making diagnosis challenging. Specific guidelines help medical professionals recognize this complex illness.
Purpose of Diagnostic Criteria
Diagnostic criteria for lupus standardize identification, ensuring consistent diagnosis across clinical settings. These criteria also provide a uniform framework for classifying patients, facilitating research on disease progression, treatment effectiveness, and clinical trials. The American College of Rheumatology (ACR) developed these criteria to classify individuals with lupus, distinguishing it from other conditions. This framework assists clinicians and researchers in understanding the disease.
The 11 Criteria Defined
The 11 diagnostic criteria for lupus, established by the American College of Rheumatology, describe various disease manifestations. These criteria characterize how lupus affects the body.
Malar Rash
The first criterion is a Malar Rash, often called a “butterfly rash” due to its distinctive shape. This red or purplish rash typically appears across the cheeks and the bridge of the nose, usually sparing the skin folds around the nostrils. It can be flat or slightly raised and may become more prominent with sun exposure.
Discoid Rash
Next is a Discoid Rash, characterized by raised, red patches with adherent scales and follicular plugging. These lesions are often circular or coin-shaped and can appear on the face, scalp, or other body areas. Discoid lesions can lead to permanent scarring or changes in skin pigmentation.
Photosensitivity
Photosensitivity refers to an unusual skin reaction to sunlight, causing a rash. For people with lupus, exposure to ultraviolet (UV) light can trigger skin flares or worsen existing symptoms, affecting up to three-quarters of individuals with the condition. This reaction can also involve systemic symptoms like fatigue and joint pain.
Oral Ulcers
Oral Ulcers are typically painless sores found in the mouth or nose. These ulcers can appear on the roof of the mouth, inside the cheeks, or on the lips and may be an early sign of lupus activity or indicate a flare-up. While often not painful, they can become uncomfortable during disease flares.
Arthritis
Arthritis involves non-erosive inflammation of two or more peripheral joints. This means the joints show signs of tenderness, swelling, or effusion without causing permanent destruction or deformity of the bone. Joint pain and swelling are common symptoms experienced by individuals with lupus.
Serositis
Serositis is the inflammation of the serous membranes lining organs, specifically pleuritis or pericarditis. Pleuritis involves inflammation of the lining around the lungs, causing chest pain, while pericarditis is inflammation of the sac surrounding the heart, which can lead to chest pain or fluid accumulation around the heart. Both can be documented by physical examination or imaging.
Kidney Disorder
A Kidney Disorder, also known as lupus nephritis, indicates kidney involvement. This can manifest as persistent protein in the urine (proteinuria) or the presence of cellular casts, which are microscopic tube-shaped particles made of cells or protein found in urine. Kidney damage can progress and may require dialysis or a kidney transplant in severe cases.
Neurologic Disorder
A Neurologic Disorder refers to conditions affecting the brain or nervous system, such as seizures or psychosis, that are not caused by medications or metabolic imbalances. Lupus can affect the central nervous system in various ways, leading to a range of neurological symptoms.
Hematologic Disorder
Hematologic Disorder involves abnormalities in blood cell counts. This can include hemolytic anemia, where red blood cells are destroyed prematurely; leukopenia, a decrease in white blood cells; lymphopenia, a reduction in lymphocytes; or thrombocytopenia, a low platelet count. These abnormalities often reflect the immune system’s attack on blood components.
Immunologic Disorder
An Immunologic Disorder refers to the presence of specific autoantibodies or other immune system abnormalities. This includes antibodies to double-stranded DNA (anti-dsDNA) or the Sm nuclear antigen (anti-Sm), which are highly specific for lupus. A false-positive syphilis test, confirmed by specific tests, can also indicate an immunologic disorder.
Antinuclear Antibody (ANA)
A positive Antinuclear Antibody (ANA) test is a common finding in lupus.
How Criteria Aid Diagnosis
The 11 ACR criteria guide lupus classification, though diagnosis involves comprehensive clinical judgment. Traditionally, a person meets criteria with at least four features, occurring simultaneously or sequentially. This threshold helps categorize patients for research, but diagnosis is not solely based on this count.
A positive Antinuclear Antibody (ANA) test is present in nearly all individuals with lupus and is often the initial screening. However, a positive ANA alone is insufficient for diagnosis, as healthy people can also have a positive result. Medical professionals consider symptoms, physical examination findings, and various laboratory tests beyond ANA for an accurate diagnosis. Some individuals experience symptoms for years before a definitive diagnosis, highlighting lupus’s complex and evolving nature.